Method for producing a monocrystalline layer of lithium niobate by transferring a seed layer of yttria-stabilized zirconia to a silicon carrier substrate and epitaxially growing the monocrystalline layer of lithium niobate and substrate for epitaxial growth of a monocrystalline layer of lithium niobate
A process for producing a monocrystalline layer of LNO material comprises the transfer of a monocrystalline seed layer of YSZ material to a carrier substrate of silicon material followed by epitaxial growth of the monocrystalline layer of LNO material.
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This application is a national phase entry under 35 U.S.C. § 371 of International Patent Application PCT/IB2019/000200, filed Mar. 26, 2019, designating the United States of America and published as International Patent Publication WO 2019/186263 A1 on Oct. 3, 2019, which claims the benefit under Article 8 of the Patent Cooperation Treaty to French Patent Application Serial No. 1800256, filed Mar. 28, 2018.
TECHNICAL FIELDThe present disclosure relates to a process for producing a monocrystalline layer of lithium niobate (LNO) material and a substrate for the epitaxial growth of such a monocrystalline layer of LNO material.
BACKGROUNDCertain materials are not currently available as a monocrystalline substrate in the form of a large-diameter wafer. Moreover, certain materials may be available in large diameter but not with certain characteristics or specifications in terms of quality, in particular, with regard to the density of defects or the required electrical or optical properties.
BRIEF SUMMARYThe present disclosure aims to overcome these limitations of the prior art by providing a process for producing a monocrystalline layer of LNO material and a substrate for the epitaxial growth of such a monocrystalline layer of LNO material. In this way it is possible to address the problem of size of the monocrystalline substrates of LNO material currently available.
The present disclosure relates to a process for producing a monocrystalline layer of LNO material comprising the transfer of a monocrystalline seed layer of yttria-stabilized zirconia (YSZ) material to a carrier substrate of silicon material followed by epitaxial growth of the monocrystalline layer of LNO material.
In advantageous embodiments, the monocrystalline seed layer has a thickness of less than 10 μm, preferably less than 2 μm, and more preferably less than 0.2 μm.
In advantageous embodiments, the transfer of the monocrystalline seed layer of YSZ material to the carrier substrate of silicon material comprises a step of joining a monocrystalline substrate of YSZ material to the carrier substrate followed by a step of thinning of the monocrystalline substrate of YSZ material.
In advantageous embodiments, the thinning step comprises the formation of a weakened zone delimiting a portion of the monocrystalline substrate of YSZ material intended to be transferred to the carrier substrate of silicon material.
In advantageous embodiments, the formation of the weakened zone is obtained by implanting atomic and/or ionic species.
In advantageous embodiments, the thinning step comprises detaching at the weakened zone so as to transfer the portion of the monocrystalline substrate of YSZ material to the carrier substrate of silicon material, in particular, the detaching comprises the application of thermal and/or mechanical stress.
In advantageous embodiments, the joining step is a molecular adhesion step.
In advantageous embodiments, the monocrystalline seed layer of YSZ material is in the form of a plurality of tiles each transferred to the carrier substrate of silicon material.
In advantageous embodiments, the carrier substrate of silicon material comprises a detachable interface configured to be detached by means of a laser debonding technique and/or chemical attack and/or by means of mechanical stress.
The present disclosure also relates to a substrate for epitaxial growth of a monocrystalline layer of LNO material, characterized in that it comprises a monocrystalline seed layer of YSZ material on a carrier substrate of silicon material.
In advantageous embodiments, the monocrystalline seed layer of YSZ material is in the form of a plurality of tiles.
In advantageous embodiments, the carrier substrate of silicon material comprises a detachable interface configured to be detached by means of a laser debonding technique and/or chemical attack and/or by means of mechanical stress.
The present disclosure also relates to a process for producing a monocrystalline layer of LixKyNazTi1NbmO3 material having a lattice parameter close to that of the LNO material comprising the transfer of a monocrystalline seed layer of YSZ material to a carrier substrate of silicon material followed by epitaxial growth of the monocrystalline layer of LixKyNazTi1NbmO3 material.
The present disclosure also relates to a process for producing a monocrystalline layer of LixKyNazTi1NbmO3 material having a lattice parameter close to that of the LNO material comprising the transfer of a monocrystalline seed layer of SrTiO3 or CeO2 or MgO or Al2O3 material to a carrier substrate of silicon, sapphire, Ni or Cu material, followed by epitaxial growth of the monocrystalline layer of LixKyNazTi1NbmO3 material.
Other features and advantages of the present disclosure will be better understood from reading the following detailed description with reference to the appended drawings, wherein:
To improve the readability of the figures, the various layers are not necessarily shown to scale.
DETAILED DESCRIPTIONIt should be noted that the thermal expansion coefficient of the carrier substrate 100 dominates the thermal behavior of the substrate for epitaxial growth of a monocrystalline layer of LNO material 10 during the step of epitaxially growing 3′ the monocrystalline layer 300 of LNO material. This is due to the low thickness, preferably less than 1 μm, of the monocrystalline seed layer 200 of YSZ material relative to the total thickness of the substrate for epitaxial growth of a monocrystalline layer of LNO material 10, which is of the order of several tens to hundreds of μm. Incidentally, the YSZ material is chosen so as to provide a monocrystalline seed layer having a lattice parameter that is as close as possible to the lattice parameter chosen for the monocrystalline layer 300 of LNO material, preferably the lattice parameter in the relaxed state in order to allow epitaxial growth resulting in as few defects as possible in the monocrystalline layer 300 of LNO material. Incidentally, the material of the carrier substrate 100 advantageously has a thermal expansion coefficient, which is particularly close to the thermal expansion coefficient of the LNO material for the same reasons of decreasing defects in the monocrystalline layer 300 obtained by epitaxy. Preferably, a carrier substrate 100 of sapphire material would therefore be used for the present disclosure.
The various embodiments described in conjunction with
Since the thin layer of silicon has a predetermined thickness (which may vary between 5 nm to 600 nm, or even thicker depending on the intended application), it could thus be used to form microelectronic components and thus allow the co-integration of components based on LNO materials in a single substrate.
Thus, after having formed the monocrystalline layer (3001, 3002, 3003) by epitaxy, it is also possible to conceive joining this structure to a final substrate and detaching, at the detachable interface 40, a part of the carrier substrate 100″. The final substrate may thus provide additional functionalities, which are, for example, incompatible with parameters of the growth carried out previously (for example, final substrate of flexible plastic type or final substrate comprising metal lines). Additionally and in general, the detachable interface is not necessarily located inside the carrier substrate but may also be located at the interface with the seed layer of YSZ material joined to this carrier substrate (for example, a stack of a layer of silicon nitride between two layers of silicon oxide allows laser debonding, particularly suitable for a carrier substrate of sapphire type) as already described in conjunction with
Claims
1. A process for producing a monocrystalline layer of lithium niobate (LNO) material, comprising:
- joining two silicon wafers to form a carrier substrate of silicon defining a detachable interface within the carrier substrate of silicon, the detachable interface including a joint between the two silicon wafers including one surface of the two silicon wafers that is roughened;
- transferring a monocrystalline seed layer of yttria-stabilized zirconia (YSZ) material directly onto the carrier substrate of silicon including joining a monocrystalline substrate of YSZ material to the carrier substrate of silicon; and
- epitaxially growing the monocrystalline layer of LNO material on the monocrystalline seed layer of YSZ material,
- wherein the joining the monocrystalline substrate of YSZ material to the carrier substrate of silicon comprises molecular adhesion of the monocrystalline substrate of YSZ material to the carrier substrate of silicon, the molecular adhesion including bonding the monocrystalline substrate of YSZ material to the carrier substrate of silicon at ambient temperature and annealing a bonding interface between the monocrystalline substrate of YSZ material and the carrier substrate of silicon to consolidate the bonding interface.
2. The process of claim 1, wherein the monocrystalline seed layer has a thickness of less than 10 μm.
3. The process of claim 2, wherein the joining the monocrystalline substrate of YSZ material to the carrier substrate is followed by thinning the monocrystalline substrate of YSZ material.
4. The process of claim 3, wherein the thinning comprises forming a weakened zone delimiting a portion of the monocrystalline substrate of YSZ material to be transferred to the carrier substrate of silicon.
5. The process of claim 4, wherein the formation of the weakened zone comprises implanting atomic and/or ionic species into the monocrystalline substrate of YSZ material.
6. The process of claim 4, wherein the thinning comprises detaching at the weakened zone so as to transfer the portion of the monocrystalline substrate of YSZ material to the carrier substrate of silicon.
7. The process of claim 3, wherein the monocrystalline seed layer of YSZ material is in the form of a plurality of tiles each transferred to the carrier substrate of silicon.
8. The process of claim 3, wherein the detachable interface is configured to be detached by a laser debonding technique and/or chemical attack and/or by application of mechanical stress.
9. The process of claim 1, wherein the monocrystalline seed layer has a thickness of less than 2 μm.
10. The process of claim 1, wherein the monocrystalline seed layer has a thickness of less than 0.2 μm.
11. The process of claim 1, wherein the transfer of the monocrystalline seed layer of YSZ material to the carrier substrate of silicon comprises joining a monocrystalline substrate of YSZ material to the carrier substrate, followed by thinning the monocrystalline substrate of YSZ material.
12. The process of claim 6, wherein detaching at the weakened zone so as to transfer the portion of the monocrystalline substrate of YSZ material to the carrier substrate of silicon comprises application of a thermal and/or mechanical stress to the monocrystalline substrate of YSZ material.
13. The process of claim 1, wherein the monocrystalline seed layer of YSZ material is in the form of a plurality of tiles each transferred to the carrier substrate of silicon.
14. The process of claim 1, wherein the detachable interface is configured to be detached by a laser debonding technique and/or chemical attack and/or by application of mechanical stress.
15. The process of claim 1, wherein the annealing is performed at a high temperature up to 1100° C.
16. A substrate for epitaxial growth of a monocrystalline layer of lithium niobate (LNO) material, comprising;
- a monocrystalline seed layer of yttria-stabilized zirconia (YSZ) material directly on a carrier substrate of silicon; and
- wherein the carrier substrate of silicon comprises two silicon wafers joined together defining a detachable interface, the detachable interface including a joint between the two silicon wafers including one surface of the two silicon wafers that is roughened.
17. The substrate of claim 16, wherein the monocrystalline seed layer of YSZ material is present in the form of a plurality of tiles.
18. The substrate of claim 16, wherein the detachable interface is configured to be detached by a laser debonding technique and/or chemical attack and/or by application of mechanical stress.
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Type: Grant
Filed: Mar 26, 2019
Date of Patent: Nov 28, 2023
Patent Publication Number: 20210095391
Assignee: Soitec (Bernin)
Inventor: Bruno Ghyselen (Seyssinet)
Primary Examiner: Kenneth A Bratland, Jr.
Application Number: 17/042,737
International Classification: C30B 25/18 (20060101); C30B 29/30 (20060101); C30B 33/06 (20060101); H01L 21/762 (20060101);